With the recent progress of the wireless technology, connections to the Internet in various wireless communication systems have been prevailed and a mobile communication environment in a mobile environment has been provided utilizing the advantages of the wireless. As a portable terminal, function has been progressed and one terminal device can connect to a different types of networks (for example, a wireless LAN (Local Area Network), a wired LAN, a portable telephone network, a PHS (Personal Handy Phone system) network. Thereby, one terminal device can connect to various types of network and, for every use, the optimal communication environment can be selected.
Because of the emergence of techniques (such as Mobile IPv6 and Lin6) that enable a continuous service in a wireless communication between different networks, it is becoming possible to receive a service without interruption even when the communication is switched by selecting an optimal communication environment for each use. A technique has been proposed that varies the quality of receive data corresponding to a change of the state of communication involved in the switching between networks through which the wireless communication is executed (see, for example, Patent Document 1).
On the other hand, a wireless data communication executed while moving is unstable because a radio wave intensity varies or the communication is interrupted due to the movement, or the transmission bandwidth considerably changes when moving into a different wireless network. A method has been proposed of executing control of the network switching and control of data quality by providing a means of notifying an upper layer of the above mentioned lower-layer information (see Patent Document 2).    Patent Document 1: Japanese Laid-Open Patent Publication No. 2004-272563    Patent Document 2: Japanese Laid-Open Patent Publication No. 2004-266330